In recent years, scanner systems have been widely used in the field of printing platemaking. There are various recording devices which employ image-forming methods using a scanner system, and the recording light sources for these scanner system recording devices include glow lamps, xenon lamps, tungsten lamps, LED's, He-Ne lasers, argon lasers, semiconductor lasers and the like.
Various characteristics are required of photosensitive materials used in such scanners, and in particular, since they are exposed with a short-duration exposure of 10.sup.-3 -10.sup.-9 seconds, it is an indispensable condition that they are of a high speed and high contrast even under such conditions. In the field of facsimiles in particular, it is important that they are outstanding in their applicability to rapid processing since a rapid information transferability is regarded as important, and there has been a strong demand for the development of photosensitive materials having a high speed and high contrast since there is a desire to increase the line count and contract the light beam for purposes of increasing the speed of scanning and obtaining a high image quality in the future.
Iridium compounds are effective in increasing the speed, hardening the gradation and improving development acceleration properties in view of such requirements, and techniques involving these are described, for example, in JP-A-48-60918, JP-A-58-211753, JP-A-61-29837, JP-A-61-201233 and JP-B-48-42172 (as used herein, the term "JP-A" means an "unexamined published Japanese patent application" and the term "JP-B" means an "examined Japanese patent publication").
However, silver halide emulsions in which iridium salts have been introduced frequently end up by also improving the low-intensity reciprocity failure while simultaneously improving the high-intensity reciprocity failure. For this reason, there has been the problem that the handling properties in a safelight are markedly impaired.
In order to resolve such problems, the coloring of a photographic emulsion layer or another hydrophilic colloid layer is often carried out by means of colorants which absorb light of a specific wavelength region. Such techniques are described, for example, in U.S. Pat. Nos. 1,845,404, 2,493,747, 3540,887, 3,560,214, JP-B-31-10578 and JP-B-39-22069. However, even though the use of such colorants frequently has little effect on the photographic emulsion itself, there are the disadvantages that they bring about spectral sensitization in unnecessary regions in spectrally sensitized emulsions and they bring about a reduction in speed which is thought to originate in the desorption of sensitizing dyes.
In addition, they can remain after processing due to the greater rapidity of development processing which has come to be carried out in recent years. There have been proposals to use dyes with a high reactivity with sulfite ions in order to overcome this, but there are the disadvantages that the stability in the photographic film is not sufficient in such cases, there is a reduction in density over time and the desired photographic effects are not obtained.